One of the most popular and visually striking leaves around, this microgreen is also called "hearts on fire." The leaves of red veined sorrel have a bold red stem and veins that run up the flatter, but structured, leaves. The flavor is sour and can be powerful depending on leaf size. As a microgreen, its flavor is more intense than that of the larger leaves of a mature sorrel plant. Even a small amount of this beautiful red veined sorrel can balance the flavors of a plate.